Magnetic Encoder Wiring and Programming
 

Hi Everyone, does someone knows how to wire the Magnetic encoder in the Sidecar or in the roboRIO and does someone knows how to program a magnetic encoder in labview?
The Magnetic Encoder number is AS5145B, Eval Kit.
Thanks, Go #1382

Re: Magnetic Encoder Wiring and Programming
 

Last year, we used this sensor and it worked reliably. To wire it, we used a low pass filter to average the PWM signal. There are instructions to build the filter on page 18 of the datasheet here:

http://ams.com/eng/Products/Position...ensors/AS5145B

Do note that when used in this way, the sensor outputs a value proportional to it's absolute position, so it can be used like a potentiometer. For us this was perfect as we were not counting number of rotations, but rather what angle the shaft was within a rotation.

The pinouts are on page 4. +5v is pin 16, and Gnd is pin 7. We wired these to the digital sidecar last year, but I think you can wire them right to the DIO on the RoboRio.

Re: Magnetic Encoder Wiring and Programming
 

Or you can use the FPGA to measure the pulse width? WPILib counter object semi-period mode.

http://www.chiefdelphi.com/forums/sh...32&postcount=5

Re: Magnetic Encoder Wiring and Programming
 

You can also use it like a normal ecoder with A and B channels.
This article is very helpful:

http://wpilib.screenstepslive.com/s/...control-system

Re: Magnetic Encoder Wiring and Programming
 

Semi-period mode is not ideal for this sensor, because the data sheet recommends using the duty cycle. When there is motion, you could get out of sync values if you're trying to measure the duty cycle in semi-period mode. You could measure just the high or low pulse and use other methods to calibrate out the 5% frequency tolerance.

Re: Magnetic Encoder Wiring and Programming
 

Good catch (paragraph 8.2 of the AS5145B datasheet).


The same holds true for the US Digital MA3:

Do you know if there are any plans to add duty cycle decoding to FPGA?